I would be very wary about using MDF.Its a dangerous material when not treated with the utmost repect.The glue that is used in the process  contains Urea Formaldehyde.which is released when cutting or planing it.this can last months if the material is not sealed with paint,or something similar soon after.Its carsenagenic,(cancercausing Agant),but also causes problems to eyes n lungs.You are suppose to wear proper facemasks when using in a confined space.Also remember any entrance through MDF screw holes nails lets the Formaldehyde seep out,unless you seal it as you go.Take a look at world reports about this material before you think of using it

Personally ive never nor will ever use MDF.My layout is built with 4mm marine plywood